Should parameters be used as variables in Lua?

Question

I've been told in Java that I should avoid modifying the original parameters such as

public int doStuff(int begin, int end) {
  /* loop or something */
  begin++; //bad
  end--; //also bad
  /* end loop */
  return
}

instead, I should do something like

public int doStuff(int begin, int end) {
  int myBegin = begin; //something like this
  int myEnd = end;
  /* stuff */
  return
}

So, I've been doing this in lua

function do_stuff(begin, last)
  local my_begin = begin
  local my_last = last
  --stuff
  my_begin = my_begin + 1
  my_last = my_last - 1
  --stuff
end

But, I'm wondering if

function do_stuff(begin, last)
  --stuff
  begin = begin + 1
  last = last - 1
  --stuff
end

is also discouraged, or is it nice and concise?

Answer 1

There are no rules. Let taste, clarity, and need decide.

Nevetheless, a common idiom is to provide default values for parameters as in

function log(x,b)
   b = b or 10
   ...
end